Gear forming

ABSTRACT

GEARS HAVING THE TEETH EXTENDING AT ANGLES TO THE AXIS OF THE GEAR AND TO THE ROOTS OF THE GEAR TEETH ARE ROLL FORMED. THE ROLL FORMING IS PARTICULARLY ADAPTABLE TO HYPOID GEARS IN WHICH THE TEETH NOT ONLY ARE AT SUCH ANGLES BUT ALSO CURVE FROM ONE END TO THE OTHER. THE ROLL FORMING TOOL AND THE GEAR ARE POSITIONED SO THAT THE TOOL BISECTS THE ANGLE BETWEEN ADJACENT TEETH. THE TOOL ALSO CAN BE CURVED TO ENABLE THE CURVED TEETH TO BE FORMED BY USING A SIMPLE, STRAIGHT ROLLING MOTION OF THE TOOL.

Jan. 19, 1971 A. F. TREMBLAY I 3,555,870

GEAR FORMING 5 Filed March 29, 1968 5 Sheets-Sheet 1 I NVENTOR.

7 Q Q Q Q ALBERT f THEMBLAY BY Q ATTfYs.

A.- F. TREMBLAY GEAR FORMING Jan. 19, 1971 5 Sheets-Sheet z Filed March 29, 1968 INVENTOR: AL BER T F TH EMBLAX' AT T Y5.

Jan. 19, 1971 A. F. TREM BLAY 3,555,370

' GEAR FORMING Filed March 29, 1968 5 SheetsSheet 5 INVENTOR: ALBERT F THEMBLAY A. F. II'REMBLAY 3,555,870

Jan. 19, 1971 GEARIFORMING I 5 Sheets-Sheet 4.

Filed March 29, 1968 .il A

/44 INVENTOR: ALBERTF TREMBLAX ATTYS.

Jan. 19, 1971 A. F'. TREMBLAY 3,555,879

GEAR FORMING Filed March 29, 1968 5 Sheets-Sheet 5 ALBERT TRFMBL'AY ATTYE.

United States Patent 3,555,870 GEAR FORMING Albert F. Tremblay, Toledo, Ohio, assignor to Kent- Owens Machine Company, Toledo, Ohio, a corporation of Ohio Filed Mar. 29, 1968, Ser. No. 717,329 Int. Cl. B21j 9/02 US. Cl. 72-216 4 Claims ABSTRACT OF THE DISCLOSURE Gears having the teeth extending at angles to the axis of the gear and to the roots of the gear teeth are roll formed. The roll forming is particularly adaptable to hypoid gears in which the teeth not only are at such angles but also curve from one end to the other. The roll forming tool and the gear are positioned so that the tool bisects the angle between adjacent teeth. The tool also can be curved to enable the curved teeth to be formed by using a simple, straight rolling motion of the tool.

This invention relates to gear forming and more particularly to the roll forming of gears having angular teeth.

In producing gears by a roll forming technique in which cam-shaped tools are rolled across a gear blank to shape the teeth thereon, very large forces and pressures are involved. This type of gear forming is disclosed and discussed fully in my U.S. Pats. 3,096,669 and 3,292,405. While gears formed by this arrangement are superior in quality, having excellent finishes and being of coldworked, dense metal, the technique has heretofore been applied only to teeth which extend perpendicularly and symmetrically from the roots so that symmetrical forces are applied to the teeth, the supporting components, and the tool.

In accordance with the present invention, it has been discovered that the tool and the gear blank can be angularly positioned relative to one another in a manner such that the shaping forces are symmetrically distributed to the adjacent teeth and.to the forming surfaces of the tool. Consequently, the advantages of roll forming also can be achieved with gears having angular teeth. Further, by employing a tool having appropriately curved workform'ing surfaces, hypoid gears can be produced by using a straight roll forming motion without the necessity of employing any transverse motions, as would be expected in order to produce the curved teeth.

It is, therefore, a principal of the invention to provide a method and apparatus for producing gears with angular teeth.

Another object of the invention is to provide a method and apparatus for producing hypoid gears.

Other objects and advantages of the invention will be apparent from the following detailed description of preferred embodiments thereof, reference being made to the accompanying drawings, in which:

FIG. 1 is a somewhat schematic front view in elevation of an overall machine for forming gears in accordance with the invention, with parts broken away and with parts in section;

FIG. 2 is a somewhat schematic right side view in elevation of the machine shown in FIG. 1;

FIG. 3 is an enlarged view in vertical cross section taken through the tool supporting and driving headof the machine of FIGS. 1 and 2;

FIG. 4 is a somewhat schematic view in vertical section taken along the line 44 of FIG. 3 and showing the tool at the extremities of its oscillatory motion;

FIG. 5 is a front view of the gear blank and the tool of FIG. 4, particularly showing the angular position of 3,555,870 Patented Jan. 19, 1971 the tool and the gear blank, with a portion of the tool broken away and sectioned;

FIG. 6 is a view similar to FIG. 5 but showing a slightly modified tool in the same angular position;

FIG. 7 is a view in perspective of the gear blank and the tool of FIG. 5 with the tool in a raised position at the end of a stroke;

FIG. 8 is a sectional view taken along the line 8--8 of FIG. 3 and showing the cooperation of the curved teeth and the curved tool;

FIG. 9 is an overall schematic view in perspective, with parts broken away, of components of the machine for both rolling the tool over the gear blank and for indexing the gear blan-k in relation to the movement of the tool;

FIG. 10 is a vertical sectional view of the gear blank supporting and indexing mechanism employed with the machine of FIGS. 1 and 2; and

FIG. 11 is a sectional view of the supporting and indexing mechanism taken along the line 11-11 of FIG. 10.

A machine for practicing the invention is indicated at 20 in FIGS. 1 and 2 and includes a frame generally indicated at 22 comprising a base 24, an upright 26, a head 28, and guide posts 30. A bed 32 is mounted for vertical movement, being guided in part by the posts 30, and is raised and lowered by a drive unit 34 which can be of a type shown in my US. Pat. 3,096,669. A workpiece supporting and indexing unit 36 is mounted on the bed 32 and a tool supporting and driving unit 38 is carried by the machine head 28. Coordinated movement of the tool and the workpiece are achieved through a power take-off shaft 40 and additional connections to be discussed subsequently.

The tool supporting and driving unit 38 can be of the type shown in my Pat. 3,292,405, and will be discussed only briefly. A rolling tool 42 is mounted on a spindle 44 (FIGS. 3 and 4) and moves with an oscillating, rolling motion across a workpiece or gear blank 46. The spindle 44, in turn, is rotatably carried by a main shaft 48 which is driven in an oscillatory manner by a crank arm 50'. As the main shaft 48 oscillates, the spindle 44 also oscillates as it moves in an arcuate path about the axis of the shaft 48 by means of a pinion gear 52 mounted on the spindle and engaged with an internal ring gear 54. This enables each increment of the surface of the tool 42 to contact the same increment of the surface of the gear blank 46 during each stroke of the tool back and forth over the gear blank. The pitch line of the pinion and ring gear can be slightly above or below the tool to cause a small sliding movement and a burnishing action of the tool with respect to the gear blank. This provides an extremely smooth, mirror finish on the gear blank, as discussed fully in my Pat. No. 3,292,405.

With the tool surface and gear blank surface coordinated in this manner, it is possible for gear teeth varying in size and shape from one end to the other to be roll formed and also for curved gear teeth, such as those in hypoid gears, to be roll formed. This is illustrated in FIGS. 7 and 8 wherein teeth 56 of the hypoid gear blank 46 increase uniformly in size from one end to the other, as illustrated by the arrows in FIG. 7. The teeth also are transversely curved from one end to the other, as shown in FIG. 8, the curvature being in a plane generally parallel to the roots of the teeth. Projections or ridges 58 and 60 and an intermediate depression or groove 62 of the tool 42 are similarly transversely curved, as shown particularly in FIG. 8, so that the curved gear teeth can be achieved with a straight rolling action of the tool and without any transverse motion as would otherwise be expected to be necessary for forming the curved teeth. The term transverse curvature is used herein to distinguish from the conventional peripheral curvature of the projections in a plane perpendicular to the axis of rotationl of the tool.

The teeth 56 of the gear blank in this instance also extend at angles to the surfaces of the roots with one side surface 64 of each tooth being generally perpendicular to the surfaces of roots 66, and with an oppositely-facing surface 68 of each tooth extending at a substantial angle to the root. If angular teeth were roll formed, very large forces would normally be placed on the elements of the machine, causing undue wear and friction. In accordance with the invention, however, the gear blank is mounted so that a line perpendicular to the axis of rotation of the tool bisects the angle formed between the adjacent surfaces 64 and 68 of two of the adjacent teeth 56. This is illustrated particularly in FIGS. 3, 5, and 6, with the surfaces forming equal angles A1 and A2 with respect to the line or plane which is perpendicular to the axis of rotation of the tool. In this position, the axis of the gear blank also intersects the plane which is perpendicular to the axis of rotation of the tool at an acute angle. The angular relationship of the tool and gear blank is accomplished in the present instance by the design of the work positioning unit 36 but can also be achieved by positioning the tool supporting unit in a predetermined angular position with respect to the gear blank.

The same symmetrical angular relationship is achieved when a modified tool of FIG. 6 is employed. This tool has three projections or ridges 72, 7'4, and 76 instead of two but with the gear again positioned with the angle between the adjacent surfaces 64 and 68 being bisected by the line perpendicular to the axis of rotation of the tool.

The supporting and indexing unit 36 is shown more fully in FIGS. 9-11, along with the arrangement for coordinating movement of the tool and the gear blank. The unit 36 includes a platform 78 mounted at the proper angle by a framework 80* which in turn is suitably atfixed to the bed 32. A chuck assembly 82 is mounted on the platform 78- with the assembly including an outer chuck ring 84 and a movable center clamping hub 86. The hub moves up and down to release or to clamp the gear blank 46, centering and firmly holding the gear blank in the lower position by means of a wedge 88 located between the hub and the blank. The hub is connected by a shank 90 to a piston 92 located in a cylinder 94 centrally located below the hub. Fluid is supplied to the ends of the cylinder 94 by transverse passages 96 and 98 drilled in a central body 100 in which the cylinder 94- is formed. The transverse passages connect with annular passages 102 and 104 which communicate with supply lines 106 and 108. In this manner, the fluid can be supplied to the cylinder for any position of the gear blank, the chuck, and the body @100.

The gear, when in the chuck, is rotated one tooth at a time by an internal ring gear 110 affixed to the body 100, pinion gears 112 and 114, and a central, sun gear 116. The latter gears can be replaced to change the degree of indexing of the chuck for gear blanks with different numbers of teeth. The gear blank is indexed after each complete back and forth oscillatory movement of the tool. This is accomplished by a cam member 118 which engages projections of a spur disc 120 connected to the sun gear 116 through a shaft 122. A cam disc 124 having a groove 126 of a particular shape rotates with the cam member 118 and controls movement of a lever 128 through a cam follower 130. This lever 128 is connected to an index bar 132 having an indexing pin 134 engageable with indexing holes 136 in the chuck ring 84. The pin 134 enters the appropriate hole 136 after each indexing movement of the gear blank to assure that the teeth of the gear blank are in a precise position with respect to the tool. The lever 128 is spring loaded to yield in the event the pin does not enter the hole and to assure proper seating of the pin 134 in the appropriate hole 136 through over-travel designed in the cam disc groove 126.

The cam member 118 and the cam disc 124 are coordinated with the movemenmt of the tool 42. For this purpose, as shown in FIG. 9, a shaft 138 of the cam member and disc is connected by a set of bevel gears 140 to a transverse shaft 142 and through a second set of bevel gears 144 to a vertical shaft 146. This shaft is connected to the power take-olf shaft 40 of the machine head 28 and, hence, through a set of bevel gears 148 and a shaft 150 to a sprocket 152. The sprocket is connected to a drive shaft 154 through a chain 156 and a second sprocket 158, with the shaft 154 driven by a motor 160. The same shaft drives the crank 50 through a disc 162 and crank link 164. With one complete rotation of the shaft 154, the tool will oscillate back and forth through one complete stroke and the gear blank will then index one tooth when the tool is at an end of its stroke. The drive unit 34 can raise the gear blank toward the tool after the blank has been indexed 360 or the blank can be raised a much smaller amount after each complete stroke of the tool.

When the gear blank is first received by the chuck 82, a positioning pin 166 (FIG. 10) on a lever 168 is moved down between the teeth to assure that the blank is initially in a proper angular position. The lever 168 is operated through a suitable piston rod 170 and a hydraulic cylinder 172. The hydraulic cylinder can be spring loaded to urge the piston rod 170 downwardly with the blind end supplied with fiuid through a line 174, the fluid supply being controlled manually. Alternately, a double-acting cylinder can be employed.

Various modifications of the above-described embodiments of the invention will be apparent to those skilled in the art, and it is to be understood that such modifications can be made Without departing from the scope of the invention, if they are within the spirit and the tenor of the accompanying claims.

I claim:

1. A tool for rolling and burnishing a gear in which the teeth extend at angles to the axis of the gear, said gear being intended for use with another gear which rotates on an axis which is other than parallel to the axis of said gear, said tool having a projecting ridge which is adapted to fit between two teeth of said gear and to cold work and burnish adjacent side surfaces of the two teeth, said ridge being arcuate in a plane perpendicular to the axis about which the tool is intended to rotate, said ridge also being transversely curved substantially throughout its length.

2. For use with a machine for rolling and burnishing rought cut gear teeth to a predetermined depth on a gear blank which is adapted to mesh with another gear, the axes of rotation of which are not parallel, said machine including a frame, tool supporting means carried by said frame for rotation about an axis, and means for supporting the gear blank so that a Work-forming surface of a tool can project into said gear blank to a predetermined depth, a work-forming tool adapted to be rotatably carried by said tool supporting means, said tool having a peripheral surface having an outwardly-extending projection curved over its length, the center of curvature of the surface substantially coinciding wvith the axis of rotation of the tool, said projection being adapted to cold work and burnish adjacent side surfaces and the root of adjacent teeth of the gear blank, said projection varying in transverse cross section substantially throughout its length, being larger at one end than at the other, and being transversely curved throughout its length.

3. A tool for displacing metal to shape teeth on a workpiece by rotation about an axis, a section through said tool taken in the plane of rotation being generally in the shape of a sector, said tool having a projection and an adjacent groove forming two oppositely-facing side surfaces, said side surfaces being adapted to engage and burnish two side surfaces of the teeth, said tool sector being longer than the length of the teeth being formed on the workpiece, and said projection being transversely curved throughout its length to form a curved tooth While moving only in the plane of rotation.

4. Apparatus for displacing metal to form teeth on a workpiece by rotation about an axis, said apparatus comprising a tool having a body and a groove forming two oppositely facing side surfaces, said side surfaces being adapted to engage and burnish two side surfaces of the teeth, said tool having an outwardly extending projection curved over its length, the center of curvature of the curved surface of said projection substantially coinciding with the axes of rotation of the tool, said projection varying in transverse cross section substantially throughout its length, a tool supporting and driving unit for moving said tool in an oscillatory manner in a plane perpendicular to the axes of rotation thereof, and a positioning and indexing unit for positioning a gear blank so that said side surfaces of said tool can project into said gear blank to a predetermined depth, and so that the angle defined by the adjacent side surfaces of the adjacent teeth to be formed on the blank is bisected by a plane perpendicular to the axes of rotation of said tool.

References Cited UNITED STATES PATENTS RICHARD J. HERBST, Primary Examiner G. P. CROSBY, Assistant Examiner U.S. Cl. X.R. 

